Method of forming metal foils



June 23, 1931. G. YUNGBLUT ET AL 1,811,485

METHOD OF FORMING METAL FOILS Filed Jan. 9, 1925 "n HA l ATTORNEYS Patented June 23, 1931 UNITED STATES PATENT OFFICE GIBSON YUNGBLUT, OF DAYTON, KENTUCKY, AND HARRY C. FISHER, OF CINCINNATI,

OHIO, ASSIGNORS TO THE RICHARDSON COMPANY, OF LOCKLAND, OHIO, A COR- PORATION 0F OHIO METHOD 0F FORMING METAL FOILS Application filed January 9, 1925. Serial No. 1,456.

Our invention relates to methods of forming metal foils without mechanical reduction, by the flotation of metal in finely divided form by surface tension on an electrolyte, and by means of forming contact with the film uniting the film into an integral foil, by an electrical treatment. A

In the production of foils in the past, the great expense has been the mechanical reduction to very fine gauge, so much so that it has been proposed to eect a saving by plating a precious metal onto a less precious one, an then by means of acid', eating away the less precious metal.

Our process has four steps, first the supporting of a film of finely divided metal, preferably in nascent form suspended on an electrolyte by means of surface tension, second the uniting of the particles of the film together into an integral foil, by means of an electrolytic operation, third the subsequent increasing of the foil to a desired thickness by an electroplating operation, and

finally finishing the surface by bufring and rolling, and giving the proper treatment by heat for annealing.

By our process it is practical to form a metal foil continuously, and pass the foil through the several treatments for finishing in a continuous web. Foils of even thickness can be produced and the process is very inexpensive as compared to present processes.

Depending upon what kind of metal is desired for the foil, we proceed to first establish a film thereof, in finely divided form on the surface of an electrolyte. It is best chemically to precipitate the metal from its salts and use the precipitate in the film forming. This precipitate is formed in the preparation plant, and is withdrawn to a container for spongy metal. An emulsifier is provided into -which the spongy metal precipitate is introduced, together with water, from a water source, and benzol from a benzol source, and agitation is set up. The proportions in the emulsion will vary with the kinds of metal used, and dilute acid will assist in the emulsification step.

When the emulsion is formed, it can be made a more or less continuous process by a duplication of emulsifiers, the emulsion maybe poured onto the surface of a water bath" where it will fioat. The water bath is kept hot enough to drive off the benzol which is passed through a benzol condenser and returned to the first step of the process. When the benzol has been 'driven off, the metal will be found floating in a film which film may then be transferred or floated onto the surface of an electrolytic bath, such as is to be used in plating preferably the kind of metal which is held in the emulsion.

In depositing the metal on the electrolyte,

- the best mode of procedure we have followed,

is to first deposit it on a bath of hot water, kept hot by steam, or otherwise, and there to remove the benzol from the metal by evaporation. The finely divided metal, with no insulation by benzol, is then maintained on the surface. When coated with benzol the powder seeks the surface, and then the driving off of the benzol appears to retain the surface tension factor so as to float the powder. To get the powder on the surface of the electrolyte it is transferred by a travellin belt which lifts it from the Water, and carries it up over such barrier as there is between solutions and thence down onto the electrolyte, where the belt plunges under the surface. A revolving drum will serve also or some other accepted way of separation by flotation.

The powder accumulates and spreads over the surface of the electrolyte, and the thickness of the film is subject to fair control and continuously welds to the foil formed in the subsequent part of the process.

T he cathode through any mechanism which we find convenient to use forms an electrical contact and with the negative current passing out through it, the film of metal floating on the electrolyte is coalesced into a thin sheet or integral foil of even thickness.

This foil is then moved by any mechanical means which we find convenient over the surface of the electrolyte, and the positive current from the anode brings about the electroplating of the foil with the metal of the electrolyte to the degree desired.

The foil is then moved from the tank, and

through a cleanser, and then through a drymg device,l and from the drying device to an annealing furnace, and then through finishing rolls, after Which the foil will be finished.

We have not attempted'to set forth the mechanical details of the machine, as it is desired to cover the process in this application. The nature of the electrical contact element, and the mechanical devices suggested in connection with the movement of the foil and the plating step, do not require specific explanation, as they are Within the skill of the person ordinarily skilled in the art to produce.

As a matterof practice, we have found the use of a roll a convenient method of Securing our negative contact to bring about the first coalescence of the metal and the roll further is a means ot' keeping the integral foil, when formed, moving on over the electrolyte, Where the final electroplating to the desired thickness is carried on. A series of Wires, however, as indicated in the figure or any cathodic contact brings about the same coalescence.

The obtaining of free silver, copper, gold, and other metals, as chemical precipitates, requires no explanation by us, nor the nature ot the electrolyte, and electrical treatment.

Referring to the drawing, the figure is a cross section of a flotation tank H, in which We carry out our process, with the specific mechanisms through which we accomplish our results represented diagrammatically. A represents the source of supply of the finely divided metal to be coalesced and formed into foil by electrolytic fiotation. B represents thefinely divided metal from Which the benzol is driven oft by the evaporation due to the heat as it is being deposited. C represents the film of metal as itis being coalesced or Welded and formed into a foillike sheet by the electrolytic action of the cathode E from which a series of Wires are extended into contact with the film by Which We introduce a means for the return of the negative current to the electrical supply G. F represents the anode Which receives the positive current from the source of the elec.- trical supply G. Ve represent the electrolyte at D.

Having thus described our invention, what We claim as new and desire to secure by Letters Patent, is y l. A method of making foil which consists in forming an emulsionv of finely divided metal, driving off the emulsifying agent While same is supported on a liquid, and uniting the film into a foil by establishing'contact therewith to make of the lfilm a cathode, said film being supported at this stage particularly, on an electrolyte.

2. A process ot making metal foil, which consists in forming an emulsion bearing a chemically 'precipitated free metal, with a light hydrocarbon product, introducing said emulsion on a liquid surface, drivin off the hydrocarbon, passing the resulting lm over the surface of an electrolyte, and making contact with said film as a cathode, to unite the film into a foil.

3. A process of continuously making metal foil which consists in passing an emulsion of a chemically precipitated metal in a volatile emulsi'fying agent over the surface of heated liquid to drive off the emulsifying agent, thus leaving the metal supported in a film by surface tension, and while so suspended giving the film an electrolytic treatment to unite the particles into an integral foil, and continuously feeding away the foil.

GIBSON YUNGBLUT. .I HARRY C. FISHER. 

